It is well known in motor vehicles to provide a seat belt system in which a lap belt and a shoulder belt wrap around the occupant and are connected to the vehicle body or the vehicle seat by a seat belt buckle. Upon loading of the occupant against the seat belt, the forward excursion of the occupant is limited by the restraint of the seat belt. It has been proposed in the prior art to limit the load experienced by the occupant by providing a load limiting device in the connection between the seat belt buckle and the vehicle. It would be desirable, however, to provide a load limiting device which would be adjustable to more precisely adjust the load limiting threshold to the needs of a particular occupant, depending on the variables such as vehicle speed and occupant weight.